The article seems more like an ad for the author's favorite set up disguised as advice. Optic, sling, light, training, yada, yada, yada. Pretty much the same exact thing nearly everyone does to all of their defensive weapons.
And other than whatever rifle you have set up for longer than CQB distances a Mil Spec trigger will do just fine. And frankly even though I do have an AR set up for 200 and up, it is NOT the rifle I will grab for a long range threat. Which is a misnomer anyway. Even in extremely rural areas it's hard to imagine justifiably smoking someone at 400 yards out. Nevertheless, for the sake of preparedness for anything, having an AR set up with a GOOD scope and a nice trigger is a solid idea in theory. I would argue that your AR with the unmagnified optic doesn't need to have a $300 Gieselle trigger to be a more than adequate defensive rifle.
Train with the guns you use. And I ain't talking about just setting some targets out at the range and shooting them.